What's it called when a series of 2D cross-sections is used to represent a 3D object

And the cross sections are displayed sequentially (like a video) to give the viewer a 3D understanding of the object without actually seeing a 3d model. I think they used to do this with MRIs/CAT scans although they probably use 3d models nowadays.

Is there a name for this method of displaying a 3d object?

tomography
http://en.wikipedia.org/wiki/Tomography